HDFS的JAVA API操作
1. HDFS获取文件系统
/**
* 打印本地hadoop地址值
* IO的方式写代码
*/
@Test
public void intiHDFS() throws IOException {
//F2 可以快速的定位错误
// alt + enter自动找错误
//1.创建配信信息对象 ctrl + alt + v 后推前 ctrl + shitl + enter 补全
Configuration conf = new Configuration();
//2.获取文件系统
FileSystem fs = FileSystem.get(conf);
//3.打印文件系统
System.out.println(fs.toString());
}
2. HDFS文件上传
/**
* 上传代码
* 注意：如果上传的内容大于128MB,则是2块
*/
@Test
public void putFileToHDFS() throws Exception {
//注：import org.apache.hadoop.conf.Configuration;
//ctrl + alt + v 推动出对象
//1.创建配置信息对象
Configuration conf = new Configuration();
//2.设置部分参数
conf.set("dfs.replication","2");
//3.找到HDFS的地址
FileSystem fs = FileSystem.get(new URI("hdfs://bigdata111:9000"), conf, "root");
//4.上传本地Windows文件的路径
Path src = new Path("D:\\hadoop-2.7.2.rar");
//5.要上传到HDFS的路径
Path dst = new Path("hdfs://bigdata111:9000/");
//6.以拷贝的方式上传，从src -> dst
fs.copyFromLocalFile(src,dst);
//7.关闭
fs.close();
System.out.println("上传成功");
}
3. HDFS文件下载
/**
* hadoop fs -get /HDFS文件系统
* @throws Exception
*/
@Test
public void getFileFromHDFS() throws Exception {
//1.创建配置信息对象 Configuration:配置
Configuration conf = new Configuration();
//2.找到文件系统
//final URI uri ：HDFS地址
//final Configuration conf：配置信息
// String user ：Linux用户名
FileSystem fs = FileSystem.get(new URI("hdfs://bigdata111:9000"), conf, "root");
//3.下载文件
//boolean delSrc:是否将原文件删除
//Path src ：要下载的路径
//Path dst ：要下载到哪
//boolean useRawLocalFileSystem ：是否校验文件
fs.copyToLocalFile(false,new Path("hdfs://bigdata111:9000/README.txt"),
new Path("F:\\date\\README.txt"),true);
//4.关闭fs
//alt + enter 找错误
//ctrl + alt + o 可以快速的去除没有用的导包
fs.close();
System.out.println("下载成功");
}
4. HDFS目录创建
/**
* hadoop fs -mkdir /xinshou
*/
@Test
public void mkmdirHDFS() throws Exception {
//1.创新配置信息对象
Configuration configuration = new Configuration();
//2.链接文件系统
//final URI uri 地址
//final Configuration conf 配置
//String user Linux用户
FileSystem fs = FileSystem.get(new URI("hdfs://bigdata111:9000"), configuration, "root");
//3.创建目录
fs.mkdirs(new Path("hdfs://bigdata111:9000/Good/Good/Study"));
//4.关闭
fs.close();
System.out.println("创建文件夹成功");
}
5. HDFS文件夹删除
/**
* hadoop fs -rm -r /文件
*/
@Test
public void deleteHDFS() throws Exception {
//1.创建配置对象
Configuration conf = new Configuration();
//2.链接文件系统
//final URI uri, final Configuration conf, String user
//final URI uri 地址
//final Configuration conf 配置
//String user Linux用户
FileSystem fs = FileSystem.get(new URI("hdfs://bigdata111:9000"), conf, "root");
//3.删除文件
//Path var1 : HDFS地址
//boolean var2 : 是否递归删除
fs.delete(new Path("hdfs://bigdata111:9000/a"),false);
//4.关闭
fs.close();
System.out.println("删除成功啦");
}
6. HDFS文件名更改
@Test
public void renameAtHDFS() throws Exception{
// 1 创建配置信息对象
Configuration configuration = new Configuration();
FileSystem fs = FileSystem.get(new URI("hdfs://bigdata111:9000"),configuration, "itstar");
//2 重命名文件或文件夹
fs.rename(new Path("hdfs://bigdata111:9000/user/itstar/hello.txt"), new Path("hdfs://bigdata111:9000/user/itstar/hellonihao.txt"));
fs.close();
}
7. HDFS文件详情查看
//查看文件名称、权限、长度、块信息
/**
* 查看【文件】名称、权限等
*/
@Test
public void readListFiles() throws Exception {
//1.创建配置对象
Configuration conf = new Configuration();
//2.链接文件系统
FileSystem fs = FileSystem.get(new URI("hdfs://bigdata111:9000"), conf, "root");
//3.迭代器
//List the statuses and block locations of the files in the given path. If the path is a directory, if recursive is false, returns files in the directory; if recursive is true, return files in the subtree rooted at the path. If the path is a file, return the file's status and block locations.
RemoteIterator<LocatedFileStatus> listFiles = fs.listFiles(new Path("/"), true);
//4.遍历迭代器
while (listFiles.hasNext()){
//一个一个出
LocatedFileStatus fileStatus = listFiles.next();
//名字
System.out.println("文件名：" + fileStatus.getPath().getName());
//块大小
System.out.println("大小：" + fileStatus.getBlockSize());
//权限
System.out.println("权限：" + fileStatus.getPermission());
System.out.println(fileStatus.getLen());
BlockLocation[] locations = fileStatus.getBlockLocations();
for (BlockLocation bl:locations){
System.out.println("block-offset:" + bl.getOffset());
String[] hosts = bl.getHosts();
for (String host:hosts){
System.out.println(host);
}
}
System.out.println("------------------华丽的分割线----------------");
}
8. HDFS文件和文件夹判断
/**
* 判断是否是个文件还是目录，然后打印
* @throws Exception
*/
@Test
public void judge() throws Exception {
//1.创建配置文件信息
Configuration conf = new Configuration();
//2.获取文件系统
FileSystem fs = FileSystem.get(new URI("hdfs://bigdata111:9000"), conf, "root");
//3.遍历所有的文件
//List the statuses of the files/directories in the given path if the path is a directory.
FileStatus[] liststatus = fs.listStatus(new Path("/"));
for(FileStatus status :liststatus)
{
//判断是否是文件
if (status.isFile()){
//ctrl + d:复制一行
//ctrl + x 是剪切一行，可以用来当作是删除一行
System.out.println("文件:" + status.getPath().getName());
} else {
System.out.println("目录:" + status.getPath().getName());
}
}
}
通过IO流操作HDFS
通过IO流操作HDFS
/**
* IO流方式上传
*
* @throws URISyntaxException
* @throws FileNotFoundException
* @throws InterruptedException
*/
@Test
public void putFileToHDFSIO() throws URISyntaxException, IOException, InterruptedException {
//1.创建配置文件信息
Configuration conf = new Configuration();
//2.获取文件系统
FileSystem fs = FileSystem.get(new URI("hdfs://bigdata111:9000"), conf, "root");
//3.创建输入流
FileInputStream fis = new FileInputStream(new File("F:\\date\\Sogou.txt"));
//4.输出路径
//注意：不能/Andy 记得后边写个名 比如：/Coeus/Sogou.txt
Path writePath = new Path("hdfs://bigdata111:9000/Coeus/Sogou.txt");
FSDataOutputStream fos = fs.create(writePath);
//5.流对接
//InputStream in 输入
//OutputStream out 输出
//int buffSize 缓冲区
//boolean close 是否关闭流
try {
IOUtils.copyBytes(fis,fos,4 * 1024,false);
} catch (IOException e) {
e.printStackTrace();
}finally {
IOUtils.closeStream(fos);
IOUtils.closeStream(fis);
System.out.println("上传成功啦");
}
}
2. HDFS文件下载
/**
* IO读取HDFS到控制台
*
* @throws URISyntaxException
* @throws IOException
* @throws InterruptedException
*/
@Test
public void getFileToHDFSIO() throws URISyntaxException, IOException, InterruptedException {
//1.创建配置文件信息
Configuration conf = new Configuration();
//2.获取文件系统
FileSystem fs = FileSystem.get(new URI("hdfs://bigdata111:9000"), conf, "root");
//3.读取路径
Path readPath = new Path("hdfs://bigdata111:9000/Coeus/Sogou.txt");
//4.输入
FSDataInputStream fis = fs.open(readPath);
//5.输出到控制台
//InputStream in 输入
//OutputStream out 输出
//int buffSize 缓冲区
//boolean close 是否关闭流
IOUtils.copyBytes(fis,System.out,4 * 1024 ,true);
}
3.3.3 定位文件读取
- 下载第一块
/**
* IO读取第一块的内容
*
* @throws Exception
*/
@Test
public void readFlieSeek1() throws Exception {
//1.创建配置文件信息
Configuration conf = new Configuration();
//2.获取文件系统
FileSystem fs = FileSystem.get(new URI("hdfs://bigdata111:9000"), conf, "root");
//3.输入
Path path = new Path("hdfs://bigdata111:9000/Coeus/hadoop-2.7.2.rar");
FSDataInputStream fis = fs.open(path);
//4.输出
FileOutputStream fos = new FileOutputStream("F:\\date\\readFileSeek\\A1");
//5.流对接
byte[] buf = new byte[1024];
for (int i = 0; i < 128 * 1024; i++) {
fis.read(buf);
fos.write(buf);
}
//6.关闭流
IOUtils.closeStream(fos);
IOUtils.closeStream(fis);
}
- 下载第二块
/**
* IO读取第二块的内容
*
* @throws Exception
*/
@Test
public void readFlieSeek2() throws Exception {
//1.创建配置文件信息
Configuration conf = new Configuration();
//2.获取文件系统
FileSystem fs = FileSystem.get(new URI("hdfs://bigdata111:9000"), conf, "root");
//3.输入
Path path = new Path("hdfs://bigdata111:9000/Coeus/hadoop-2.7.2.rar");
FSDataInputStream fis = fs.open(path);
//4.输出
FileOutputStream fos = new FileOutputStream("F:\\date\\readFileSeek\\A2");
//5.定位偏移量/offset/游标/读取进度 (目的：找到第一块的尾巴，第二块的开头)
fis.seek(128 * 1024 * 1024);
//6.流对接
IOUtils.copyBytes(fis, fos, 1024);
//7.关闭流
IOUtils.closeStream(fos);
IOUtils.closeStream(fis);
}
合并文件
在window命令窗口中执行
type A2 >> A1 然后更改后缀为rar即可